11 .as you are sitting in your chair the force of gravity is pulling you down. what force is causing you to stay in the chair instead of falling through the chair?

a. applied.

b. normal.

c. gravity.

d. friction.

B

Explanation:

As you are sitting on the chair, gravity tends to pull you downwards but the normal reaction exerted by the chair is just enough to keep you from falling downwards. It works in the upward direction

Option(B).= Normal

Explanation:

Normal force is a type of contact force which is perpendicular to surface of contact of objects like the surface of chair that prevents us from falling downwards or that of table that prevents an object from falling from it.

By Newton's third law, every force has an equal and opposite reaction so when we sit on a chair the force of gravity pulls us down which is thus the force we apply on chair due to the pull and because of it, the chair applies an equal normal force on us which prevents us from falling down.

since you're a real machine, your ama is always less than your ima, because you can never totally eliminate friction.

d. air pressure decreases as altitude increases.